Attempting to use Bamboo variable ${bamboo.repository.branch.name} and not working

Trying to clone multiple repositories with the same branch name, using mercurial.

The build keeps failing stating that the variable does not exist.

I placed ${bamboo.repository.hg.branch} in the branch name in the source repository field, which works if I have a user set variable, but I want to be able to check out the repositories automatically with the auto-branching.